We are constantly reminded of the need for personal security in today's society. All too often in the news we hear of missing persons and the dramatic searches which ensue. For each heroic story of a "just-in-time" rescue of a person who is abducted, lost, in a threatening situation, or in need of emergency medical care, there are many more personal dramas which unfortunately end in tragedy. It follows that immediate notification of an emergency situation and a prompt response from police, paramedics, fire department, or another service organization are essential for the well-being of the individual.
Today's technology provides us with public services such as the 911 telephone number for rapidly summoning emergency help if we are able to access a telephone, dial the number, and communicate our location. However, these services fall short in the case of a young child, a mentally incompetent or medically incapacitated person, someone lost in the woods, or the victim of an abduction or kidnapping. These situations necessitate a security system that travels with the individual, is not limited in range, is able to define and signal an emergency situation without human intervention, and identifies the individual's location. Such a system would provide protection to the individual and peace of mind to those responsible for his or her care and well-being.
A number of prior art devices have been proposed for use as personal alarms and tracking systems, as well as to automate the dispatch of proper authorities to a person in an emergency situation. U.S. Pat. No. 4,694,284 issued to Levelle et al. discloses a collar to prevent abduction. The Levelle et al. device does not allow the user to manually activate any one of several alarm states or levels. It relies on a wide range of available receivers, such as directional radio receivers, amateur radio receivers, or television receivers to give an approximate location of the collar, not the individual, once the collar is removed.
U.S. Pat. Nos. 4,744,083, 4,839,656, and 4,965,586 issued to O'Neill disclose variations of a system that uses positioning determining satellites in a geostationary orbit. This system is intended to be used to generate terrain maps, to test message transfer link signal quality, and for determining the elevation of an object by comparing transmitted information with a stored terrain map. It is not intended for use as a personal security system, nor is it capable of being so used.
U.S. Pat. No. 4,799,062 issued to Sanderford et al. discloses a radio position determination and apparatus based on measured times-of-arrival of radio signals from a plurality of land-based transmitters. This patent is concerned with errors due to multipath (signal reflection) problems causing errors in locating the signal source.
U.S. Pat. No. 4,818,998 issued to Apsell et al. provides a system for tracking stolen motor vehicles, not individuals, using radio direction-finding methods. This system is initiated only after a delay in reporting and verification through a national database of registered users of the system. The method of using radio direction-finding techniques also delays locating the vehicle.
U.S. Pat. No. 4,819,860 issued to Hargrove et al. discloses a wrist-mounted device for sensing vital functions. It is activated only when preset pulse rate and body temperature limits are exceeded. The user relies on an emergency aircraft locator beacon to order to be found. There is no provision for a manually activated security alarm.
U.S. Pat. Nos. 4,885,571, 4,918,432, and 4,952,913 issued to Pauley et al. describe methods of monitoring prisoners confined to a "house arrest." These methods are intended for use within the restricted limits of a field monitoring device.
U.S. Pat. No. 5,021,794 issued to Lawrence discloses a personal emergency locator using UHF radio direction-finding and distance-measuring equipment to find a person. This patent only provides for remote activation by a child's parent of the wearer's locating transmitter; it does not provide for the wearer to initiate the alarm. As in other prior art of this type, this device also relies on a time-consuming method of radio direction-finding techniques and skills to eventually locate the person wearing the alarm.
U.S. Pat. No. 5,027,314 issued to Linwood et al. describes a system and method for tracking a number of subjects, each wearing a personal infrared transmitter, detected by a plurality of receivers in a pre-determined area. This system is limited to identification and tracking within line-of-sight in confined areas and does not lend itself for use in widespread geographical areas.
U.S. Pat. No. 5,196,825 issued to Young discloses an apparatus for monitoring the location of a person and determining whether the person is in distress using a transceiver and at least one remote receiver. In the monitor mode, the alarm activation apparatus must continuously transmit a signal which is used to activate the alarm. This feature has limitations due to the fact that the transmitter is always on, shortening the life of available battery power. Again, as in other references previously mentioned, the user must be located by radio direction-finding equipment.
U.S. Pat. No. 5,225,809 issued to Bunn discloses a personal security system that requires constructing a plurality of automatic direction-finding antennas in an appropriately organized and spaced relation within the geographical area to be monitored. Once a rough estimate of where the transmitting signal is located, a more precise location must be determined by the use of direction-finding equipment.
U.S. Pat. No. 5,225,842 issued to Brown et al. discloses a vehicle or any other animate or inanimate object tracking and navigation system employing GPS satellites and a remote GPS receiver. Although the Brown et al. system uses GPS technology, it does provide the advantages of an optimal personal security system. Specifically, this system does not contemplate active and/or passive alarm signal generation by a personal security device.
U.S. Pat. No. 5,334,974 issued to Simms et al. discloses a fully automatic security system to be used to protect passengers in a motor vehicle. This system also lacks certain elements of an optimal personal security system, including the ability to provide personal security independent of a vehicle and the ability of a central station to initiate a status request of the mobile unit.
U.S. Pat. No. 5,357,254 issued to Kah, Jr. discloses a location monitoring system that utilizes a radio transmitter and a radio receiver to monitor the movement of a person or object. The receiver sounds an alarm at a predetermined time after failure to receive a signal. This system requires the use of a receiver to determine range and direction to locate the user. As in other prior art of this type, Kah, Jr. '254 also relies on using a method of radio direction- and range-finding which takes time and skill to eventually locate the person wearing the alarm.
U.S. Pat. No. 5,396,227 issued to Carroll et al. discloses a system that monitors an individual for compliance with a protective order. The system is activated when the violator's transmitter is detected by the victim's receiving apparatus.
U.S. Pat. No. 5,461,390 issued to Hoshen addresses the problem for monitoring a number of prisoners within a specified boundary and is useful for "house arrest" and stalker detection. This patent relates to monitoring a subject's location and comparing the location listed on a database as to where the subject should be.
U.S. Pat. No. 5,515,419 issued to Sheffer describes a tracking system and method for tracking a movable object carrying a cellular phone unit. The phone unit includes a processor for generating the emergency signal. The location of the user is determined by the cellular phone system's identifying or control channel signals received by the phone and only gives a general location of the user.
U.S. Pat. No. 5,559,520 issued to Barzegar discloses an information system for automatically providing mobile vehicles dispatch information related to their geographical location. This system is described to provide routing information to vehicles, rather than to provide a personal security and tracking system for individuals.
Despite the above-described tracking and security devices and systems, it is important to note that the prior art generally is limited to transmitting an alarm, the source of which is located by a complex array of antennas or by a direction-finding receiver, either of which would require undue time to locate a person in distress.
Systems utilizing GPS technology for tracking vehicles have not fully addressed the requirements of a portable, personal security system. Nor do extant systems, developed for tracking a person, that are limited to applications such as monitoring prisoners within range of a field monitoring device.
Current available technology does not address the case of an individual who is helpless in an emergency situation where information is required so that the appropriate authorities can respond quickly and efficiently to a distress signal generated by the individual. Providing personal security for persons at risk demands a fully automated and responsive system for summoning assistance.
In order to meet the demands created by a situation where an individual with limited time, opportunity, or ability to generate a distress signal encounters danger, becomes lost, or experiences another condition that requires assistance, the ideal personal security and tracking system will comprise an alarm trigger and separate signaling unit, such that the signaling unit will generate an alarm signal in response to activation of the alarm trigger to enable a locating system to identify the location of the signaling unit, which should remain with the individual. The alarm could be generated by the individual directly, as by manual activation of the alarm trigger or manual activation of the signaling unit itself, or indirectly, as where the alarm trigger is removed from the individual or where the portable signaling unit becomes separated from the alarm trigger by a predetermined distance, thereby automatically generating an alarm signal. The ideal system should further allow for the generation of varying levels of alarm signals.
Further, the ideal system would use a locating system that does not constrain an individual to a given geographical area and that contains multiple redundancies to provide for faster, more accurate, and more reliable signal source location information than do known systems and devices.